EMI shielding enclosures

• US 6,485,595 B1
• Filed: 07/06/2000
• Issued: 11/26/2002
• Est. Priority Date: 05/01/1998
• Status: Expired due to Fees

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: de Souza, Jose P., Yenni, Donald M. Jr., Baker, Mark G.
• Primary Examiner(s): Ball, Michael W.
• Assistant Examiner(s): MUSSER, BARBARA J
• Application Number:
  US09/610,739
• Time in Patent Office: 873 Days
• Field of Search: 361/818, 257/659, 257/660, 174/35.GC, 174/35.MS, 156/196, 156/221, 156/309.6, 156/308.2
• US Class Current: 156/221
• CPC Class Codes: H05K 9/0026 integrally formed from metal sheet
• CPC Class Codes: H05K 9/0028 with retainers or specific soldering features
• CPC Class Codes: Y10T 156/1002 with permanent bending or reshaping or surface deformation of self sustaining lamina
• CPC Class Codes: Y10T 156/1043 Subsequent to assembly
• CPC Class Codes: Y10T 442/126 Including a preformed film, foil, or sheet
• CPC Class Codes: Y10T 442/131 Including a coating or impregnation of synthetic polymeric material
• CPC Class Codes: Y10T 442/2475 Coating or impregnation is electrical insulation-providing, -improving, or -increasing, or conductivity-reducing

Abstract

An EMI shielding enclosure, for an electronic assembly, comprising a ground plane of a printed circuit connected to a shaped EMI shielding cover. The cover results from thermoforming a composite sheet of several layers, including a carrier for a fibrous metal mat that has fibers substantially surrounded by a fiber-coat. Connection of the cover to the ground plane, to form the EMI shielding enclosure, requires the fiber-coat to adhere to the printed circuit in the vicinity of the ground plane.

Claims

1. A method for forming an EMI shielding enclosure around an electronic assembly, comprising the steps of:

(a) providing an electronic assembly, having a ground plane including a conductive trace;

(b) providing a thermoformed shielding cover having a contact edge, said shielding cover further comprising;

a non-porous carrier sheet;

a fibrous metal mat having an outer-surface and a contact surface, said contact surface adjacent said carrier sheet, said metal mat comprising low melting metal fibers that melt during thermoforming of said shielding cover; and

a resin fiber-coat applied to diffuse through said fibrous metal mat toward said non-porous carrier sheet to insulate said metal fibers, said resin fiber-coat extending less than 0.15 mm beyond said metal fibers at said outer surface of said metal mat;

(c) aligning said contact edge with said conductive trace; and

(d) adhering said contact edge against said conductive trace to form an electrical connection between said edge and said trace.

2. The method of claim 1 wherein said contact edge is adhered to said conductive trace, by the steps of:

(a) placing a heating block, having a profile edge, in close proximity to said contact edge of said shielding cover such that said profile edge heats at least a portion of said contact edge to soften said fiber coat;

(b) applying force to said heating block to urge said metallic fibers, in said portion of said contact edge, against said conductive trace to form an electrical connection therewith, said profile edge having a channel formed therein to receive said fiber coat when it softens; and

(c) cooling said portion of said contact edge to allow said fiber coat to harden to adhere proximate said conductive trace to secure said electrical connection.

3. The method of claim 1 wherein said fiber coat comprises a pressure sensitive adhesive, said contact edge being adhered to said conductive trace by applying force to said contact edge to adhere it to said trace to secure said electrical connection.

4. The method of claim 1 wherein said fiber coat comprises a pressure sensitive adhesive containing conductive particles, said contact edge adhered to said conductive trace by applying force to said contact edge to adhere it to said trace to secure said electrical connection.